Stock distributor

ABSTRACT

A FLOW CONTROL DEVICE DISPOSED BENEATH AND COMMUNICATING DIRECTLY WITH THE HEADBOX OF A PAPER MAKING MACHINE AND INCLUDING AN INLET EXTENDING TRANSVERSELY OF TNE ENTIRETY OF THE HEADBOX WIDTH FOR RECEIVING THE FLOW OF STOCK FROM A SUPPLY POINT, THE INLET COMMUNICATING WITH THE BOTTOM-MOST SECTOR OF AN EXPLOSION CHAMBER OF GENERALLY CIRCULAR CROSS SECTION EXTENDING TRANSVERSELY OF THE ENTIRETY OF THE HEADBOX WIDTH, WITH THE TOP-MOST SECTOR OF THE EXPLOSION CHAMBER HAVING AN OPENING DEFINING A CONSTRICTED PASSAGEWAY LEADING INTO THE BOTTOM OF A VERTICALLY-EXTENDING GRADUALLY-ENLARGING THROAT ALSO EXTENDING TRANSVERSELY OF THE ENTIRETY OF THE HEADBOX WIDTH AND WITH THE TOP OF THE THROAT COMMUNICATING WITH AN OPENING IN THE FLOOR OF THE POND OF THE HEADBOX, THE EXPLOSION CHAMBER CONTAINING A SINGLE ROTATABLE HOMOGENIZER ROLL AND THE TOP-MOST PORTION OF THE THROAT CONTAINING A PLURALITY OF ROTATABLE HOMOGENIZER ROLLS IN A SPACED SIDE-BY-SIDE RELATIONSHIP.

Feb. 16, .1971 A. E. H. FAIR STOCK DISTRIBUTOR Filed Aug. :50, 1968 n uI V INVENTOR. ALBERT EDWARD HAROLD FAIR BY MUZZ M %M% ATTORNEYS.

United States Patent ()1 3,563,853 Patented Feb. 16, 1971 3,563,853STOCK DISTRIBUTOR Albert Edward Harold Fair, 101 Monmouth St.,Brookline, Mass. 02146 Filed Aug. 30, 1968, Ser. No. 756,576 Int. Cl.D21f 1/ 06 US. Cl. 162-342 1 Claim ABSTRACT OF THE DISCLOSURE A flowcontrol device disposed beneath and communicating directly with theheadbox of a papermaking machine and including an inlet extendingtransversely of the entirety of the headbox width for receiving the flowof stock from a supply point, the inlet communicating with thebottom-most sector of an explosion chamber of generally circular crosssection extending transversely of the entirety of the headbox width,with the top-most sector of the explosion chamber having an openingdefining a constricted passageway leading into the bottom of avertically-extending gradually-enlarging throat also extendingtransversely of the entirety of the headbox width and with the top ofthe throat communicating with an opening in the floor of the pond of theheadbox, the explosion chamber containing a single rotatable homogenizerroll and the top-most portion of the throat containing a plurality ofrotatable homogenizer rolls in a spaced side-by-side relationship.

BACKGROUND OF THE INVENTION (1) Field of the invention The invention isprimarily concerned with means for breaking up the currents which enterthe body of the headbox and to assist in the attainment of good mixingand distribution across the width of the forming area of the papermakingmachine.

My structure allows conversion of a flowing stock stream of circularcross section to a flowing, constantlyagitated stream of rectangularcross section and thence to a flowing stream of gradually-widening crosssection, which allows the attainment of a well and uniformly dispersedmixture having a relatively slow forward velocity at the point of entryinto the headbox pond as achieved by cooperant agitation means whichinduce small multidirectional currents for keeping the fibers dispersedand, accordingly, amenable to close and uniform web formationwhereforethe strength of the formed web is generally more equalized inboth the forward and cross directions and the uniformity of the web massin all are more consistent than has been possible to achieve in anyheadbox heretofore known.

(2) Description of the prior art Relatively complicated flow devices areknown. One approach has visualized resort to multiple feeds to theheadbox by means of small pipes across the machine 'width, the stockbeing normally pumped thereto through a single pipe to a manifold havinga plurality of outlets leading into the headbox, each outlet serving,objectionably, to create its own set of currents or turbulences. Such aplurality of forward currents has led to unequal velocities between thepoints of flow, not to mention dead spots, eddies and fluctuating crosscurrents.

Numerous supplemental correctional devices have been resorted to, suchas perforated boards, adjustable partitions, racks, discs, and the like,to eliminate the created conditions. Notwithstanding various attempts tomerge these currents, it has been exceedingly ditficult to destroy themaltogether, wherefore they persist at the sluice, or slice.

Headboxes have been employed having relatively large compartments,resulting in slow flows of stock streams so that the pulp fiberssuspended in the carrier become quiet and flocculation and settlingoccur, leading to a mottled and uneven sheet. It is necessary to keepthe mass moving at a velocity sufiicicnt to preclude such state of quietand the resultant flocculation and settling. Efforts in this directioninvolving the use of a plurality of adjustable partitions haveencouraged the forming of longitudinal currents in the headbox flow andhave allowed an excess of exposed surfaces, which tend to collectfibers, and chemicals and to form incrustations.

Other systems have incorporated explosion chambers and flow manifolds.Turbulence, caused by a sudden flow enlargement or by a quick reversalof flow direction, tends to break up flocculation and to provideadditional mixing. However, it usually allows eddies, spirals and crosscurrents and induces air entrapment so as to disturb the sheet formationtechnique.

The prior constructions, aimed in various ways to solve the inherentproblems, appear consistently to be attended with certain seriousdisadvantages and limitations which have militated against their moregeneral adoption.

SUMMARY OF THE INVENTION The invention relates broadly to the control ofa confined stream of an aqueous suspension of papermaking fibers by wayof a flow control means for the spreading and quieting of such stream inthe stock conduit system of the web-forming machinery, while creating acontrolled micro-current pattern in the suspension to maintain anorganized dispersion of fibers and filling solids.

To produce a paper sheet having uniform physical properties, the paperstock delivered to the web-forming region of the machine should beevenly distributed across the machine width. The kinetic energy andpotential energy in unit areas of the stream delivered to theweb-forming region should be as uniform as possible throughout thestream cross section, and in addition, the entire stream should bemaintained in a condition which is as near to a steady-state flow as itis possible to obtain.

This invention envisions a new and novel means wherein a flow spreaderand headbox participate in a conjoint result of supplying a single,steady, wide, smooth, quiet, thoroughly-mixed, uniform stream of theaqueous suspension, free from large eddies, or flocculations, to the webforming component of the machine.

As is known, the headbox or flow box delivers to the web-forming means asuspension of fibers and other additives dispersed in a water vehicle,the delivery being at a predetermined velocity through an orifice orslice which extends laterally across the width of the machine, fordeposit upon the web-forming means. Such web-forming means, in the caseof a Fourdrinier type of machine, comprises a continuously-travellingendless wire, having a generally horizontally-extending run throughwhich, by means including capillary action and surface tension, thewater is drawn so as to leave upon the upper planar surface of the wirea mat or web of the papermaking fibers.

The principle hereof can be applied to the point of approach to any webforming machine.

The desideratum of supplying to each increment of the web-forming areaan equal and uniform distribution of fibers, under steady-state flowconditions, in the form of a moving mass of water and fibers insuspension, with each lamina thereof moving in the machine direction atthe same velocity and under such pressure as to allow a deliveryvelocity equal to the speed of the travelling forming wire, is wellunderstood and accepted in the papermaking art.

Disturbingly, a high flow velocity is usually associated with violentcurrents in the flow direction. In some cases,

the desired deflocculation is achieved, but at the expense of creatingirregularities across the web, due to uneven streams within the greatermass of fiber suspension. Such lack of uniformity deleteriously affectsthe web strength and causes unevenness which interferes with the qualityof the end product.

It is Well known that pulp fibers will flocculate or settle unlessagitated or kept in motion or caused by some physical-chemical means tooppose each other, which flocculation will cause a mottled or blotchyformation and which settling will cause a massing of fibers, with themasses breaking away and causing spots in the sheet, and if largeenough, breaks at the presses and/or at other points.

This condition presents consistent difliculties to the task ofdelivering a uniform suspension of fibers to the web-forming region, andis aggravated by the problems inherent in avoiding the formation ofcurrents in the suspension.

As to directionality, an absence of parallel flow in the machinedirection signifies a presence of cross currents which cause variationsin the quantity of fibers delivered across the lateral width of theforming area, resulting in heavy and light areas across the formedsheet. This is known as skating.

It follows, therefore, that optimum formation depends upon two factors:(1) a uniform flow of the mixture of pulp and water to the web-formingarea; and (2) a uni form dispersion of the fibers upon the carryingmedium.

BRIEF DESCRIPTION OF THE DRAWING The figure is a broken side elevationalview of a stock distributor of the invention disposed generally beneaththe headbox of a papermaking machine (not shown).

DESCRIPTION OF THE PREFERRED EMBODIMENT The outflow end of a deliverysection comprises a first or inflow or feeder conduit of generallyrectangular cross section and of a width which extends transversely ofthe headbox to the extent of the width of the headbox, all to the end ofdefining an inlet slot or adjacent slots of a cross section generallysimilar to that of a sluice.

A single fishtail or fanshaped inlet of such cross section is preferredover a plurality of circular pipes disposed in a side-by-side relation,all in order to allow a flow into the next-succeeding component with aminimum of strong individual currents.

The flow may be distributed transversely across the headbox width byother inlet systems such as by the use of a multiplicity of T conduitswherein the flow from a single conduit is broken down into subdivisionsa plurality of times preferably by multiple fishtails, before actualingress is made into the next-succeeding component.

The single fishtail type of flow spreader having a main axis extendingin a generally horizontal plane is known to comprisehorizontally-extending upper and lower walls, which walls generallydiverge away from each other between their entry and dischargeextremities and a pair of oppositely-spaced outwardly diverging sidewalls, each merging smoothly with the respective adjacent edges of theupper and lower walls, thereby to form an enclosed fan-shaped flowchamber.

By such flow spreader structure, the stock is constrained to flowhorizontally-forwardly through the fan-shaped flow chamber defining anever-widening side-to-side dimension or width.

The width of the exit extremity will correspond to the lateral width ofthe associated head box and the machine width.

Here again, it will be observed that the flow spreader has widened therectangular section progressively and gradually to the full width of themachine wherefor the stock flows therein in a constantly widening streamand flows outwardly therefrom to the related components.

The spreading length is according to the width of the flow inlet and thewidth of the flow box and the spreading angle is within limits that willpermit uniform spreading of the flow.

Stated otherwise, the fiber suspension is transformed from its flow ofcircular cross section to a flow of relatively flat cross section withinthe flow spreader and is spread evenly widthwise of the machine so as topreclude the development of uneven stock conditions at the Web formingarea.

The first conduit has an exit terminal or outflow suitably joined to asecond conduit 12 of corresponding cross section and dimensions by meansof coupled flanges 14 and 16, as shown.

As will appear, the flow to the headbox is by means of a conventionalpumping mechanism, not shown, from a supply point, also not shown,through first or inflow or feeder conduit 10 and second conduit 12.

Second conduit 12 has an inboard terminal which merges tangentially intoand communicates with the lowermost sector of an explosion chamber 20 ofgenerally-circular cross section, said explosion chamber having a widthwhich extends transversely of the headbox for the entirety of theheadbox Width.

Explosion chamber 20 is closed at its opposite ends by verticallydisposed side walls 22 and may be supported with respect to thepapermaking machine as by suitable cross rails, such as 24 or the like.

As will appear, the desideratum is to convert the flow from therectangular cross section of second conduit 12 to the round section ofexplosion chamber 20.

A throat, generally indicated by numeral 30, is essentially of a fan orfishtail configuration having a main axis extending in agenerally-vertical plane and will be seen to comprise outwardly-inclinedfront and rear walls 32 and 34 respectively, said walls generallydiverging from each other from their lower to their upper extremities,and a pair of oppositely-spaced vertically-disposed side walls 36 (onlyone of which is shown) at opposite sides of the headbox, which sidewalls 36 merge with the respective side walls 22 of the explosionchamber.

Walls 32 and 34 will be understood to extend transversely of the headboxto the extent of the width of the headbox and to be supported bysuitable webs or similar supporting members 38, walls 32 and 34connectiing to walls 36 at the respective corners in a throat-definingmanner.

The lower extremities of walls 32, 34 and 36 of the explosion chambermerge into the respective side edges of a slot 40 formed in the topmostportion of the wall of the explosion chamber and also extendingtransversely through the width of the headbox, while the upperextremities of walls 32, 34 and 36 merge into the respective floor 50,rear wall 52, and side walls 54 of the headbox, generally indicated bynumeral 60.

Thus, the throat defines a passageway having an everwidening approach tothe headbox pond.

A large quiet headbox will eliminate currents but such allows the fibersexpression of their tendency to coagulate. A smooth flow at relativelyslow speed, with the fibers at rest relative to one another, is known toallow conditions that promote flocculation, slime formation and stockaccumulation in the dead spots.

Contrariwise, a strong agitation, while mixing the fibers thoroughly anddispersing them will create the very objectionable cross currents andeddies I seek to avoid.

The design hereof, accordingly, is a compromise between the two extremesand comprehends interference devices to promote the required agitationso as to disperse the fibers.

The flow box or head box per se comprehends transversely-spacedvertically-extending side walls 54 and 54 and interconnectedtransversely-spaced vertically-extending forward and rearward walls anda bottom wall 50 to define a pond therewithin.

As is conventional, a slice, not shown, is provided, the stock and watersuspension flowing from the head box through the slice, said slicehaving the primary function to deliver a sheet of liquid of uniformthickness and equal velocity across the width of the web-forminginstrumentalities.

Explanitorily, the operation of a paper machine for a grade or type ofpaper must be such as to deliver a constant amount of fibers at alltimes. The amount of water accompanying the fiber onto the web-formingelements may be varied to improve the formation or change the qualitiesof the finished sheet. In other words, the consistency (pounds offiber/pounds of water) in the head box can be varied and the adjustmentof the top lip of the slice will allow a constant head to be maintained.For example, if the machine tender wishes to reduce the head boxconsistency by adding more water, he can raise the top slice lip,increase the opening, and still maintain the head.

A homogenizer roll 70, of the type disclosed in my patent, No. 3,224,929of Dec. 21, 1965, is disposed within explosion chamber 20, beingsuitably journalled at its opposite ends in the opposite side walls 22.

The roll may comprise a longitudinally-extending rotatable cylindricalshell or tube 72 having outwardlyprojecting solid trunnions at oppositeends of said shell for insertion through the respective adjacent sidewall of the explosion chamber in suitable journal or bearing meansmounted in said side walls whereby the agitating unit may be positionedbetween and intercoupled with the confining opposite explosion chamberwalls in running. relationship therewith.

On the outer peripheral surface of shell 72, a multiplicity ofradially-arranged outwardly-extending fins or vanes 74 are stationarilysecured, each fin or vane being disposed angularly or obliquelyrelatively to the longitudinal axis of the shell.

The fins are grouped as groupments or sets, the fins of each groupmentor set being arranged in a longitudinally-extending row in equi-spaceddistance from each, other and parallel relationship as to each other,with the axis of the row being parallel to the longitudinal axis of theshell.

The fins of a groupment or set divide the surface area of the shellalong the axis thereof as defined by said groupment or set into aplurality of substantially equal segmental sections.

The fins of one set in one row and the fins of another set in theadjacent row are disposed in angularly intersecting planes as the shellis rotated.

The rows, there being 4 in number in the illustrated embodiment, areequidistant from each other, they being disposed approximately 90 fromeach other, though it will be understood that the number of rows can bevaried so that the angle therebetween may be greater than or less thansaid 90.

As to their angular or oblique disposition, the fins of adjacent rowsare alternately disposed to eifectuate the reversing of cross currentswhich serve to mix the stock and to reorient the fibers so that many ofthem will have their longitudinal axes at right, or approximately right,angles to the direction of flow instead of being aligned with the flow,as is normal, thereby serving to tend to equalize directional strengthand to aid in the formation of the web.

Further as to their angular or oblique disposition, the fins of oneaxial row may be arranged at a certain angle relative to the shelllongitudinal axis, and the fins of the next adjacent axial rows arepreferentially, though not obligatorily, arranged at an angle opposed tothe said certain angle in the said one axial row for purposes ofeffectuating, upon the shell rotation, opposing sets of miniature orlocalized cross currents in the sense that the set of miniature orlocalized cross currents enduced by the said one axial row are opposedby the set of miniature or localized cross currents induced by the saidadjacent axial row to allow a wobbling or back-andforth movement, onwhich is repeated over and over as the shell is rotated. Thereby ashearing action results which causes the stock to be deflected first inone direction and then in the opposite direction so as to allow completeoverlapping and intermingling before delivery to the throat 30,simultaneously avoiding stock flocculation and minimizing thedevelopment of erratic eddy currents and other non-uniform flowconditions.

Stated otherwise, the adjacent rows function to establish a wobbling orconstantly changing movement in the flow of the stock stream flowingtherepast, to the end that the assemblage functions as an improved meansfor insuring more random distribution of the fibers.

A rotative movement is imparted to the homogenizer roll by a powermeans, not shown.

As the shell is rotated within a single cycle of 360 of rotation, thefins present segments of mutating planes relative to the axis of theshell so as to create the said wobble action by impelling the stockfirst in one direction and then in another whereby the flow istransversely broken into a plurality of very fine cross currents. Thefins rotate to impart a wobble efiect to the streams, as they flowbetween the fins and then flow into and merge with adjacent eddies toeffect the ultimate desired interweaving and uniform fiber distributionin the sheet formation. By such rotative movement, the shive problemwherein the fibers tend to deposit and to string on the fins and theshell is solved.

The function of the roll in the explosion chamber is to subject thestock to direct agitation so as to destroy any longitudinal currentsbefore they enter the throat. Such agitation also precludes anystagnation or clotting or lumping or adhering of fibers to the explosionchamber walls or to the components of the roll for the reason that theactivity in this area is so great as to avoid same.

The roll is placed in such manner as to act upon the inflow into theexplosion chamber and at the same time to avoid any short circuiting,being slightly offset with respect to the main central axis of theexplosion chamber.

The rearward edge of slot 40 will be observed to be lower than or belowthe horizontal plane of the forward edge of the slot so as to permitavoidance of the throw naturally generated by the rotating ofhomogenizer roll 70, all to the end that currents are cut as they enterthe explosion chamber. That is, the turning of the roll against thecurrents and dispersing them, will tend to throw the flow to theafterchamber and to force same toward the papermaking machine, followingthe left hand side of the explosion chamber wall as viewed in thedrawing. The arrangement as shown offsets this effect.

A pair of homogenizer rolls 80, also of the general design as taught inmy earlier patent, supra, are disposed in the topmost portion of throat30, each being journalled in the opposite side walls 36.

The rolls are disposed in the same horizontal plane in manner such thattheir agitator fins or blades reach upwardly into the lower planes ofthe pond as they are rotated.

The rolls are close together so that, whereas relatively high velocitieswill occur in the throat, there is an inherent tendency for the stock tostagnate at lower velocities. The new currents of desirablecharacteristics are created by the homogenizing action, in the pondprior to the slice. In effect, the rolls serve to put life into thefibers of the suspension in the pond.

The number of homogenizer rolls used in this position will depend uponthe required dimensions of the head box, which involves volumesconsistant with quantities suspension required for a given range of webproduction.

The rolls generally comprehend an arrangement and operation of aplurality of units disposed in manner to keep the pond alive, toeliminate flocking, to destroy objectionable currents, and to betterprepare the stock for delivery to the slice and the forming wire or moldunder controlled conditions of uniform velocity flow.

Basically, by such rolls, I provide means whereby the stock stream meetsidentical resistance across its entire width and is evenly fed to theforming surface at a single, selected velocity. Simultaneouslytherewith, I cure other specific prior art defects inclusive of theformation of light and heavy streaks running in the machine direction atregular or varying spaced intervals across the machine width by thedeliberate and intentional creation of a pattern of a multiplicity ofminute cross currents for effecting improved random dispersion of thefibers.

As known, a momentary speed increase followed by a sudden speed decreasecreates small eddy currents which break up fiber flocs. Pin racks,perforated plates and rolls have all been heretofore used for thispurpose.

The agitating units hereof effectuate a reduction in area through whichthe fluid flows.

At the point of reduced area, the stock velocity is increased and uponmoving past the agitating unit or units, the velocity of stock and wateris again decreased.

Rotative movement is imparted to each roll by a power means, not shown.Preferably the rolls are rotated in opposite directions and in timedrelation to the rate of stock flow, though they may be rotated in thesame directions, if desired, and/or at varying rates of speed so thatthey are rotated either in unison or out of unison and at constant orvariable speeds.

By the employment of a multiplicity of such rolls at the inlet to thepond, the agitating action is spread over the entirety of the areawithin the throat discharge and the pattern of fine currents createdthereby is spread out with the currents gently overlapping each other soas to enhance the uniformity.

As the fins are rotated within a 360 cycle, they circumscribe a wobblingeffect as they each rotate about a point defining the center of theshell. Being so mounted, they produce a fine pattern of rapidlyrecurring and reversing currents. That is, they present segments ofmutating planes so as to impart an oscillatory motion to the streams ofstock passing therebetween and thereby effectuate the randomdistribution of the fibers uniformly and evenly at all points throughoutthe length of the roll as the converging streams intermingle upon havingpassed between the fins on the roll.

The rolls of the pair are disposed in alignment as to each other in aplane angularly related to the horizontal axis of the stock in the pondthereabove.

All prior art headbox designs have one feature in common; the rectifyingrolls thereof, whether stacked longitudinally with respect to the flowor otherwise do not effectively destroy the longitudinal flow patterns.Holey rolls of prior art designs do not help to obviate the clottingeffect. As the indenting moves toward spreaders of larger size and toflows of greater speeds, the holey rolls in effect tend to serve as damsand to dam the flow so that clotting above the rolls frequently results.The usual technique to prevent this clotting is to lower the pond levelbut such only further restricts the flow.

Herein, I provide agitating units within the headbox transversely of theflow so as to effectuate a breaking in the pattern at every one-quarterturn of each said unit.

The rate of turning contemplated is within a ratio of 2:1 and 10:1,relative to the rate of forward flow past the agitators, all so as toeffectuate a continuous and repetitive pattern of small cross currents.

It is believed that the gist of the invention will be clearly understoodfrom the foregoing disclosure and accordingly, further analysis thereofat this point is considered unnecessary, as I have in accordance withthe provisions of the patent statutes, described the construction andprinciple of operation of my invention together with the apparatus whichI believe to represent one of the best embodiments thereof, to the endthat others can, by applying current knowledge, readily adapt it forvarious applications without omitting features which, from thestandpoint of prior art, fairly constitute essential characteristics ofits generic and/or specific aspects.

The claims are desired to include within the scope thereof all of saidsuitable variations, modifications and equivalents by whichsubstantially the results of the invention may be obtained through theuse of substantially the same or equivalent devices or means.Accordingly, limitation hereof should only be made as determined by aproper interpretation of the prior art and the scope of the subjoinedclaims, in which it is my intention to claim all novelty inherent hereinas broadly as possible.

I claim: 1. In a flow control apparatus of the class describedcomprising:

a primary conduit for containing a flowing stream of fluid,

said primary conduit being laterally-diverging and increasing in widthfrom its inflow to its outflow,

an explosion chamber of substantially circular cross section and of awidth complemental to the width of the primary conduit at its outflowend and having a slot formed therein and extending transversely throughthe width thereof,

the rearward edge of the slot being disposed below the horizontal planeof the forward edge of the slot,

a throat disposed vertically above the explosion chamber andcommunicating with the slot,

the throat being fan-shaped and having a general configuration of wallsconverging away from each other from their lower to their upper ends,

a headbox communicating with and disposed vertically above the throat,

primary agitating means comprising a rotatable finned homogenizer rollwithin the explosion chamber disposed parallel to but slightly offsetwith respect to the main central axis of the explosion chamber, and

secondary agitating means comprising at least two rotatable finnedhomogenizer rolls disposed within the throat in the same horizontalplane adjacent the discharge into the headbox.

References Cited UNITED STATES PATENTS 6/1964 Fair l62342X 12/1965 Fairl62342

